1. Field of the Invention
This invention relates to the selection of paper feed trays in a xerographic printing machine, and in particular to the means for dynamically selecting the tray to be used for sheet feeding.
2. Description of the Prior Art
It is a generally known and desirable practice to automatically switch between paper input trays while running a printing job on a xerographic printing machine. This technique allows the operator to utilize two or more paper supply trays, thereby enabling the filling of one tray while feeding sheets from the other tray. Automatically feeding from a second paper tray, upon detecting that a first tray is empty, results in more efficient use of the printing machine resources.
U.S. Pat. No. 4,804,997 to Mizude et al. discloses a specific cassette selection apparatus having a plurality of removable paper feed cassettes. The apparatus includes an identification device, a specific copying mode selection device, and a paper feeding cassette selection device. The cassette selection device responds to paper-size identification signals and a copying mode selection signal to select a cassette for use in the selected copying mode. The apparatus has three paper feed cassettes and a display means which indicates the proper cassette.
U.S. Pat. No. 4,725,869 to Umezawa et al. discloses a display device of a copying machine which in a special mode such as duplex copying, judges whether the paper feed cassette for copying is proper for the mode selected. If so, the cassette is displayed. If not, applicable feed cassettes are displayed successively. The device further displays not only the non-selection of a proper feed cassette, but the type of cassette.
U.S. Pat. No. 4,860,049 to Toshimitsu et al. discloses an image forming apparatus which has three paper feed cassettes and cassette selection keys which are used to select one of the three cassettes.
U.S. Pat. No. 4,734,747 to Okuda et al. discloses a copying machine with a copy paper detection device in which there is provided a means for detecting the amount of copy paper present in a paper storing means and judging whether the amount of copy paper present exceeds the number of copy sheets designated to be copied. The device has a cassette selecting key and a cassette size display for selection of any of three paper feed cassettes.
U.S. Pat. No. 4,393,375 to Sugira et al. discloses a control system for a copying apparatus which minimizes user error and provides a compact control console. An information display member is capable of sequentially displaying an identification of discrete operating features. Control members are capable of inputting signals for a number of different operating features. The specific discrete operating features are automatically displayed after a predetermined set time.
While the references cited above disclose many methods for determining the correct paper tray for use on a printing job, none disclose the ability to automatically switch between an empty tray and a full tray holding the same type of paper stock. It is however, generally known to have an electrophotographic reproduction machine capable of switching between two paper feed trays or cassettes. This type of "autoswitching" feature is found on some high volume regrographic machines available on the market today. However, not currently available on today's reprographic and printing machines are means to control or limit an operator's selection of an alternate paper source during the execution of a copying or printing job. Specifically, the advantage in allowing the operator to manually switch paper trays during job execution results in increased operator flexibility in controlling the copying task. Conversely, the reason for limiting the scope of the alternate selections is so that the operator will not be able to view, and therefore, will be unable to select features that would disrupt the progress of the current copying job. Furthermore, by limiting the display to only features which may be altered during execution of a job, the user interface is simplified and an operator will be less likely to become confused or frustrated by attempting to select features which are unavailable for alteration during job execution.
It is, therefore, an object of the present invention to provide the operator maximum flexibility to alter machine operation in a manner conducive to obtaining the desired output characteristics, while eliminating the possibility of disrupting the execution of the current copying operation. It is another object of the present invention to provide an interface selection for the enablement of an automatic tray switching feature. It is a further object of the present invention to allow an operator to select a subset of the available paper trays to be used as a set of alternate trays which will be used to assure that a continuous supply of paper is available for the execution of a copying or printing job. It is yet another object of the present invention to allow an operator to dynamically alter the tray currently used for paper feeding during the execution of a printing job. It is an additional object of the present invention to limit the set of alternate paper trays available for dynamic selection by an operator to those identified during the programming of the automatic tray switching feature. It is yet another object of the present invention to display the subset of non-selected alternate trays available for dynamic selection, during execution of a printing job, thereby providing an operator with increased flexibility. It is a final object of the present invention to use an interactive video display to select the paper tray to be used for paper feeding, thereby eliminating the need for mechanical switches located on each of the paper supply trays.
Further advantages of the present invention will become apparent as the following description proceeds and the features characterizing the invention will be pointed out with particularity in the claims annexed to and forming a part of this specification.